Angiotensinergic Innervation of the Human Right Atrium: Implications for Cardiac Reflexes (original) (raw)
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Role of cardiac sympathetic nerves in blood pressure regulation
Autonomic Neuroscience, 2014
Stellate ganglionectomy (SGx) was used to assess the contribution of cardiac sympathetic nerves to neurogenic hypertension in deoxycorticosterone (DOCA)-salt treated rats. Experiments were conducted in two substrains of Sprague-Dawley (SD) rats since previous studies reported bradycardia in Charles River-SD (CR-SD) rats and tachycardia in SASCO-SD (SA-SD) rats with DOCA treatment suggesting different underlying neural mechanisms. Uninephrectomized male rats underwent SGx or SHAM surgery and were instrumented for telemetric monitoring of mean arterial pressure (MAP) and heart rate (HR). After recovery, 0.9% saline solution and DOCA (50 mg) were administered. Baseline MAP (Days 0-5 average) after SGx in CR-SD rats (96 ± 2 mm Hg; n = 7) was not significantly different (p = 0.08) than CR-SD SHAM rats (103 ± 3 mm Hg; n = 9); however, there was a significantly lower HR during the baseline period (377 ± 7 vs. 432 ± 7 bpm, p b 0.05) in SGx rats. In SA-SD rats baseline MAP was not different between SGx and SHAM rats and HR was lower in SGx rats (428 ± 8 vs. 371 ± 5 bpm, p b 0.05). After DOCA treatment in both substrains, MAP and HR were elevated similarly in SHAM and SGx groups showing minimal impact in both groups of SGx on hypertension development. However, overall MAP in SA-SD SHAM rats reached a significantly higher level (155 ± 10 mm Hg vs 135 ± 5 mm Hg, p b 0.05) than that observed in CR-SD SHAM rats demonstrating that the magnitude of hypertensive response to DOCA-salt treatment varies between substrains. In conclusion, removal of cardiac sympathetic nerves did not alter the development or maintenance of DOCA-salt hypertension in SD rats.
Experimental Physiology, 2005
It is now well accepted that the sympathetic nervous system responds to specific afferent stimuli in a unique non-uniform fashion. The means by which the brain transforms the signals from a single type of receptor into an appropriate differential sympathetic output is discussed in this brief review. The detection of and response to venous filling are used for illustration. An expansion of blood volume has been shown in a number of species to increase heart rate reflexly via sympathetic nerves and this effect is primarily an action of volume receptors at the venous-atrial junctions of the heart. Stimulation of these volume receptors also leads to an inhibition of renal sympathetic nerve activity. Thus the reflex response to an increase in plasma volume consists of a distinctive unique pattern of sympathetic activity to maintain fluid balance.
Heart Autonomic Nervous System: Basic Science and Clinical Implications
Autonomic Nervous System [Working Title], 2022
The heart has an intrinsic conduction system that consists of specialized cells. The heart receives extensive innervation by both sympathetic and parasympathetic systems of the ANS. The ANS influences most heart functions by affecting the SA node, AV node, myocardium, and small and large vessel walls. The sympathetic system carries an excitatory effect on heart functions. Conversely, the parasympathetic system has inhibitory effects on heart functions. ANS abnormalities in terms of anatomy and physiology can cause various heart abnormalities. ANS abnormalities associated with electrical abnormalities can cause a variety of heart manifestations. Besides electrical abnormalities, ANS also correlates with ischemic heart disease. Following electrical and ischemic instability, ANS also have direct effect on action potential duration restitution. By understanding the mechanism of influence of the anatomy and physiology of the ANS heart and its influence on various heart abnormalities, we ...
AJP: Heart and Circulatory Physiology, 2007
Although ANG II exerts a variety of effects on the cardiovascular system, its effects on the peripheral parasympathetic neurotransmission have only been evaluated by changes in heart rate (an effect on the sinus node). To elucidate the effect of ANG II on the parasympathetic neurotransmission in the left ventricle, we measured myocardial interstitial ACh release in response to vagal stimulation (1 ms, 10 V, 20 Hz) using cardiac microdialysis in anesthetized cats. In a control group ( n = 6), vagal stimulation increased the ACh level from 0.85 ± 0.03 to 10.7 ± 1.0 (SE) nM. Intravenous administration of ANG II at 10 μg·kg−1·h−1 suppressed the stimulation-induced ACh release to 7.5 ± 0.6 nM ( P < 0.01). In a group with pretreatment of intravenous ANG II receptor subtype 1 (AT1 receptor) blocker losartan (10 mg/kg, n = 6), ANG II was unable to inhibit the stimulation-induced ACh release (8.6 ± 1.5 vs. 8.4 ± 1.7 nM). In contrast, in a group with local administration of losartan (10 mM...
Initiation of the cardiac cycle is myogenic, originating in the sinuatrial node (SA). It is harmonizied in rate, force and output by autonomic nerves which operate on the nodal tissues and their prolongations, on coronary vessels and on the working atrial and ventricular musculature. All the cardiac branches of the N.vagus, X. cranial nerve, (parasympathetic) and all the sympathetic branches (except the cardiac branch of the superior cervical sympathetic ganglion) contain both afferent and efferent fibres; the cardiac branch of the superior cervical sympathetic ganglion is entirely efferent. Sympathetic fibres accelerate the heart and dilate the coronary arteries when stimulated, whereas parasympathetic (vagal) fibres slow the heart and cause constriction of coronary arteries. Preganglionic cardiac SY (sympathetic) axons arise from neurones in the intermediolateral column of the upper four or five thoratic spinal segments. Some synapse in the corresponding upper thoratic SY ganglia, others ascend to synapse in the cervical ganglia; postganglionic fibres from these ganglia form the SY cardiac nerves (from ganglion cervicale sup. goes N.cardiacus cervicalis sup.; form ganglion cervicale med. Goes N.cardiacus cervicalis sup.; from ganglion cervicothoracicum(stellatum) goes N.cardiacus cervicalis inf.; from ganglion thoracicum I-IV go Nn.cardiaci thoracici). Preganglionaric cardiac PSY (parasympathetic) axons arise from neurones in either the dorsal vagal nucleus ambiguus; they run in vagal cardiac branches to synapse in the cardiac plexuses and atrial walls. In man (like in most mammals) intrinsic cardiac neurones are limited to the atria and interatrial septum, and are most numerous in the subepicarial connective tissue near the SA and AV nodes.
Nerve Centers Affecting the Function of the Cardiovascular System
Journal of Babol University of Medical Sciences, 2021
BACKGROUND AND OBJECTIVE: The activity of the cardiovascular system is carried out by the Autonomic Nervous System (ANS). ANS itself is controlled by multiple nerve centers. At present, there is little and scattered information about them in Persian language. The aim of this review article is to collect information about nerve centers that control ANS and their relationship with cardiovascular activity in Persian. METHODS: In this review article, by searching the international and national databases of web of science, Scopus, Google Scholar, PubMed, ISC and Magiran until 2020 and using the keywords cardiovascular system, baroreflex, the rostral ventrolateral medulla (RVLM), the caudal ventrolateral medulla (CVLM), the nucleus tractus solitarius (NTS), the hypothalamic paraventricular nucleus (PVN), the hypothalamic supraoptic nucleus (SON), amygdala, raphe nucleus, the periaqueductal gray (PAG), cuneiform nucleus (CnF), the rostral ventromedial medulla (RVM) and the pedunculopontine tegmental nucleus (PPT), data about Autonomic Nervous System were collected. FINDINGS: Evaluations have shown that the most important brain centers for regulating blood pressure are the rostral ventrolateral medulla, the nucleus tractus solitarius, the hypothalamic paraventricular nucleus, the periaqueductal gray, and raphe nucleus, which control cardiovascular activity mainly by affecting the sympathetic system. CONCLUSION: According to the results of this study, the maintenance of basal blood pressure, heart rate regulation and reflex control of blood pressure and heart rate are mainly done by autonomic and especially sympathetic nerve centers.
2007
Chronic intravenous angiotensin II (Ang II) has been widely used to establish centrally mediated hypertension in experimental animals, and disruption of Ang II activity is a frontline treatment for hypertensive disease. However, the acute central actions of circulating Ang II are poorly understood. We examined the effects of intravenous pressor doses of Ang II on autonomic activity in anaesthetized rats under neuromuscular blockade, and compared baroinhibition evoked by Ang II pressor ramps to equipressor responses evoked by phenylephrine (PE). Baroinhibition of splanchnic sympathetic nerve activity was attenuated during Ang II trials compared with PE, and rats remained sensitive to electrical stimulation of the aortic depressor nerve at higher arterial pressures during Ang II trials. This was not due to a direct effect of Ang II on aortic nerve baroreceptors. In a separate series of experiments, we provide direct evidence that bulbospinal barosensitive neurones in the rostral ventrolateral medulla are differentially sensitive to pressure ramps evoked by Ang II or PE vasoconstriction. Nineteen out of 41 units were equally sensitive to increased arterial pressure evoked by Ang II or PE. In 17 of 41 units, barosensitivity was attenuated during Ang II trials, and in five of 41 cases units that had previously been barosensitive increased their firing rate during Ang II trials. These results show, for the first time, that circulating Ang II acutely modulates central cardiovascular control mechanisms. We suggest that this results from activation by Ang II of a central pathway originating at the circumventricular organs.